Rock PBR Texture Creation within Blender (Procedural) for export in game engines
I worked ten minute or so and get these. I used two Voronoi for displacement, Clouds and Marble noise for surface diffuse and normal map. I doesn't look really good but you can create these blocky rockey surface like this using Volonoi as displacement map. But I really don't think it worth the effort...maybe you can do "Substance Designer" kind of things in blender, but blender is not specialized for these purpose. Unless you write custom plug-in for those kind of works, It's like digging your grave with a spoon.